Distributing your bitcoins in more than one wallets will save you in the future and El Salvador knows this.
No, this is not correct. Don't open threads on topics which you do not understand. Distributing to more addresses or wallets does not do anything to safeguard against quantum computers. What is important is whether an address has been reused or not.
Even without quantum computing threat, I do not like to hold my coins on a single wallet. I have at least 3 different bitcoin wallets because I think it is better than having just only one.
It is not. Three averagely secured wallets is worse than one with maximum security.
Hacker will start attacking first Satoshi wallet before them if they are afraid of this risk in the future which they will have time to react before their wallet will be hacked.
You are making an assumption that may not be true. Satohi's addresses are a prime target through which mass panic can be caused which would lead to fast security upgrades. Instead, silently compromising a wallet here and there would be a better approach.